That evening, a soldier at the Finnish National Defense Forces’ measuring station in Kajaani, southern Finland, recorded an abnormal increase in background radiation. He reported it to the operational center in Helsinki, but no further action was taken. Late that night, the plume encountered rain clouds over Sweden, and the moisture in them began to scavenge and concentrate the contaminants it contained. When the rain finally fell from the clouds, around the city of Gävle, two hours’ drive north of Stockholm, it had become heavily radioactive.
